The present invention relates generally to vapor canisters for vehicles and, more particularly, to a valve assembly for a vapor canister of an evaporative emission system in a vehicle.
It is known to provide a fuel tank in a vehicle to hold fuel to be used by an engine of the vehicle. It is also known to provide a vapor recovery and storage or evaporative emission system for the vehicle to reduce evaporative emissions of the fuel from the vehicle. Typically, the evaporate emission system includes a vapor canister remotely mounted such as in an engine compartment of the vehicle and operatively connected by separate external valves and lines to the fuel tank. However, the evaporative emission system is prone to permeation losses, has limited vapor storage capacity, and limited vapor flow rate acceptance.
New low emission vehicle requirements greatly reduce the amount of evaporative emissions allowed from the vehicle. The low levels now required effectively move the emissions from the xe2x80x9cbreakthroughxe2x80x9d levelxe2x80x94where the canister""s carbon capacity was fully utilizedxe2x80x94to the xe2x80x9cbleedxe2x80x9d level. These bleed emissions are hydrocarbon vapors that escape to atmosphere through migration of the canister""s hydrocarbon heel. The vapor canister""s bleed emission performance can be greatly improved with increased flow path length through the carbon bed. These features allow the carbon closest to the fresh airport to be very well purged and keep the migrating hydrocarbon vapors away from atmosphere. While increasing the flow length of the carbon bed is possible, the shape of the vapor canister is frequently constrained by vehicle packaging space. Additionally, a very efficient flow length to cross-sectional area ratio can increase flow restriction, resulting in a negative impact on on-board refueling vapor recovery (ORVR) performance.
Therefore, it is desirable to integrate a valve assembly into a vapor canister and reduce bleed emissions. It is also desirable to provide a valve assembly in a vapor canister that greatly reduces an opening for bleed performance, while allowing low restriction flow. It is further desirable to provide a valve assembly in a vapor canister that lowers cost, lowers evaporative emissions, and is easier to package in a vehicle.
It is, therefore, one object of the present invention to provide a valve assembly for a vapor canister in a vehicle.
It is another object of the present invention to provide a valve assembly for a vapor canister in a vehicle that reduces bleed emissions.
It is yet another object of the present invention to provide a valve assembly for a vapor canister in a vehicle that greatly reduces an opening for bleed performance while still allowing for low restriction flow.
To achieve the foregoing objects, the present invention is a valve assembly for a vapor canister including a partition adapted to be disposed in an interior chamber of the vapor canister and having at least one opening extending therethrough. The valve assembly also includes a valve connected to the partition and covering the at least one opening and being movable to provide variable flow of fluid therethrough.
One advantage of the present invention is that a valve assembly is provided for a vapor canister in a vehicle that reduces bleed emissions through partitioning of a carbon bed of the vapor canister. Another advantage of the present invention is that the valve assembly incorporates a variable flow opening into a horizontal partition or at the atmosphere port of a vapor canister, thereby lowering costs. Yet another advantage of the present invention is that the valve assembly has a variable opening that allows for low flow restriction for ORVR and purge, but limits the opening during low flow situation, greatly improving low emission vehicle performance. Still another advantage of the present invention is that the valve assembly is relatively simple and inexpensive. A further advantage of the present invention is that the valve assembly does not attempt to seal the opening, just reduce the size of the opening during low flow conditions, eliminating the need for additional components such as springs, etc. Yet a further advantage of the present invention is that the valve assembly greatly reduces the opening for bleed performance, while still allowing for low restriction flow.